Small Engines (Lawn Mowers, etc.): Electronic Ignition, cast iron cylinder, air fuel mixture

Question
I have just purchased a Craftsman tiller, (Modle#636-299950)
It has no fire.  After checking with Sears I find  the Ignition Coil is no longer available and the Ignition Trigger is $299.20.  I'm not sure that the Ignition Coil is bad, how can I check it?  Is there another type Ignition Trigger I can use in place of the $299.20 one?  I have no idea what type motor it is, it was made in Japan and has a cast iron cylinder liner, it looks to be very well built, it is a 5hp flat head.

Blessings and thanks for you help
Jim

Answer
James
When you say you just purchased this equipment do you mean New??
Did you buy it from someone? Let me know E-mail me at gb@gbelect.net I will have to research this I can get you the parts allot cheaper than sears. Try looking for the model # or any other numbers on the engine that is very important. As far as sears they have it as a discontinued engine. Only for them this engine still has parts available.
To check the coil If your mower is less than 15 years old, there is an excellent chance that if uses an electronic ignition system. These are very reliable as there are no points or condenser to go bad and no need for routine tune-ups.

However, a number of other problems can result in lack of spark:

Make sure stop switch/stop wire is in appropriate position - confirm with a multimeter, check that flywheel is being spun by starter and that flywheel key is intact to assure proper timing, check condition of points/condenser and setting (if applicable), test magnet (on flywheel) for strength, check the gap between flywheel and magneto core.

All common lawn mower engines require a precisely timed spark to ignite the air-fuel mixture in the cylinder. The existence of a spark can easily be tested as follows:

WARNING: make sure there is no gas in the vicinity when performing the following test!

Remove the spark plug wire and insert the blade tip of an appropriately sized and well insulated (plastic) screwdriver inside the boot or clip in place of the spark plug. While holding the *insulated* part of the screwdriver, position the metal part of the blade about 1/8th inch from the block or frame.

An alternative technique is to use an old, but good, spark plug whose gap has been increased to about 1/8 inch or one specially made for exactly this purpose. In this case, simply connect the spark plug wire to the test plug and hold its threaded part against the cylinder head or other part of the chassis (away from the gas tank!!).

Note: Just positioning the spark plug wire a short distance from the spark plug terminal is not recommended as the results of this test will then depend on the condition of the spark plug as well since the spark will have to jump two gaps.

Have a buddy crank the engine at normal starting speed so that you will be able to hold the screwdriver or test plug steady and be close enough to see any spark clearly. Shield the gap from the sun or bright light if necessary.

You should see a nice healthy spark jump the gap several times on each pull (actually, once per rotation of the crankshaft/blade on both 2 and 4 stroke engines). Note: 4 stroke engines ignite the air-fuel mixture on every other rotation of the crankshaft. The extra sparks fire harmlessly into the exhaust gasses and are wasted. Can you believe it?!

CAUTION: if you are not well enough insulated, *you* will jump several times per rotation of the crankshaft/blade if the ignition system is functioning properly! Hey, that *is* a valid test!

If this test confirms the spark, it is still possible that the spark plug is fouled or bad. See the section